Police arrested 31 people in Ferguson, Mo., after coming under “heavy gunfire” overnight, officials said Tuesday, as the deployment of National Guard in a very limited role failed to prevent a new night of violence in the racially charged town.

Police say they need military-grade weapons to counter heavily armed drug dealers, mass shooters and terrorists. Armored vehicles can be used against barricaded gunmen, to evacuate citizens in emergencies or to quell riots, while high-powered, automatic rifles keep police from being outgunned by bad guys. But the growing militarization of local police is raising alarms across the country.

WASHINGTON — The Defense Department is pushing back against criticism that it’s helping militarize local police forces by supplying them with surplus gear.

“We don’t push equipment on anybody … It is made available to law enforcement agencies if they want it and if they qualify for it,” Pentagon Press Secretary Rear Adm. John Kirby said Tuesday. “There’s a lot of due diligence here. This isn’t some program run amok.”

The DOD’s 1033 Program is a congressionally mandated initiative that enables law enforcement agencies to obtain equipment and weapons that the military no longer needs. State and local authorities have to apply for the items and explain to the Defense Logistics Agency why they need them.

The program has been in place since the 1990s but has come under intense scrutiny in recent days as police in Ferguson, Mo., have appeared on national television armed with assault rifles and military vehicles while clashing with demonstrators.

Since 2007, DOD has given the Ferguson Police Department two Humvees, one generator and one cargo trailer. Over the same time period, law enforcement agencies in St. Louis County, which Ferguson is a part of, received six pistols, 12 rifles, 15 weapon sights, a bomb-disposal robot, three helicopters, seven Humvees and two night-vision devices, according to Kirby.

Authorities in Ferguson have been trying to quell violent protests that erupted after the Aug. 9 shooting death of Michael Brown, an unarmed 18-year-old African-American, by a white police officer.

Critics have said the response was a heavy-handed approach that escalated tensions in the town and may have fueled violent protests. Some believe that the 1033 program has blurred the lines between law enforcement and the military.

But the Pentagon disagrees.

“We’re not going to give more equipment or equipment that’s inappropriate for use by a law enforcement agency that’s small and doesn’t need it … Just because they ask for a helicopter doesn’t mean they get a helicopter,” Kirby said.

“There’s a lot of thought that goes into this. We’re not militarizing law enforcement,” Kirby insisted.

Kirby suggested it would be a mistake to get rid of the program..

“My hunch is that many of these [law enforcement] agencies out there would tell you that some of this equipment saves lives and protects citizens. And so while we’re all focused on what’s going on in Ferguson … let’s be careful not to throw the baby out with the bath water here,” he said.

While voicing support for the initiative, Kirby sought to distance DOD from any potential misuse of the gear.

“It still is up to local law enforcement to determine how and when and where and under what circumstances they use excess military equipment,” he said. “We don’t take a position on the way the equipment is being used.”

But as criticism of the program mounts, Secretary of Defense Chuck Hagel is taking a look at it.

“The secretary has been mindful of the public debate and discussion about this issue, and asked his staff this morning for some additional information about the program … and he’s consuming that now,” Kirby said.

On Monday, President Barack Obama suggested that the program should be reviewed, but no such review is in the works at this point.

“Secretary Hagel has not ordered a review of this program. He’s simply asked for some more information so that he can have a more informed opinion about it,” Kirby said.

“If after the secretary dives into this more, or if he deems it appropriate to conduct a review or a study, you know, he wants to potentially change it, then we’ll certainly come up and talk to you about that. But right now, we’re simply trying to get a little more detail about it.”